This invention relates to an image communication apparatus and, more particularly, to an image communication apparatus capable of communicating color images by facsimile transmission and to a method of controlling this apparatus.
In a conventional color-image communication apparatus, the receiving machine uses the 68th bit of a facsimile information field (FIF) in a digital identification signal (DIS) to notify the transmitting machine of whether or not it possesses a JPEG encoding function and uses the 69th bit of the FIF in the DIS signal to notify the transmitting machine of whether or not it possesses a full-color mode function. On the other hand, the transmitting machine uses the 68th bit of the FIF in a digital command signal (DCS) to instruct the receiving machine to perform JPEG encoding communication by the 68th bit of the FIF in a digital command signal (DCS) and uses the 69th bit of the FIF in the DCS signal to instruct the receiving machine to perform full-color mode communication.
In this conventional procedure, it is necessary for the transmitting machine to notify the receiving machine of the number of lines in a case where communication of a color image is executed in accordance with the JPEG standard. The method of giving notification of the number of lines includes communication procedures of two types, namely a first communication procedure in which zero lines is reported as the number of lines by JPEG-image-related information (JPEG information) transmitted before the JPEG image and notification of the number of lines actually transmitted is given using a JPEG marker DNL, and a second communication procedure in which notification of the number of lines is given by JPEG information at the start.
Further, facsimile transmission schemes are of two types, namely a scheme in which a scanned image is stored in memory temporarily and a so-called direct transmission scheme in which an image is transmitted while it is being scanned. In the case of direct transmission, the number of lines is reported to the receiving machine through the first communication procedure because the number of lines cannot be reported before image transmission.
However, in a case where transmission of a color image is performed through the first communication procedure, in which notification of zero lines is initially given by the JPEG information and notification of the number of lines actually transmitted is given by the JPEG marker DNL, there are instances where a communication error occurs in the machine receiving the Ad communicated image. A communication error of this kind tends to occur especially in personal computers equipped with software having a facsimile send/receive function. Further, in a case where communication is performed through the first communication procedure, the color facsimile transmission is carried out upon reporting the number of lines by the same method even when the image is re-transmitted after the occurrence of the error. This means that once the above-mentioned error occurs, the problem cannot be resolved by re-transmission.
Accordingly, an object of the present invention is to provide an image communication apparatus and method of controlling the same in which even if a procedure for reporting the number of lines gives rise to an error in the receiving machine, the occurrence of the same error can be prevented when a message is re-transmitted to the receiving machine.
Another object of the present invention is to so arrange it that even when a communication error occurs on the receiving side owing to the first communication procedure through which the number of lines of an image is reported as zero lines before transmission of image information and the number of lines actually transmitted is reported by a JPEG marker DNL in color image communication of a JPEG image, the second communication procedure, which reports the number of lines of the image before the image information is transmitted, is adopted when the image information is re-transmitted, thereby making it possible to perform color facsimile communication in reliable fashion.
According to the present invention, the foregoing objects are attained by providing an image communication apparatus capable of communicating JPEG images by color facsimile transmission, comprising: transmitting means capable of transmitting a JPEG image through a first procedure, which is for reporting number of lines of the JPEG image as zero lines to a receiving destination before the JPEG image is transmitted and then subsequently transmitting the JPEG image; and re-transmitting means which, if a communication error occurred at the receiving destination in a case where an image was transmitted by the transmitting means in accordance with the first procedure, is for re-transmitting image information through a second procedure, which is for reporting the number of lines of the JPEG image to the receiving destination before the JPEG image is transmitted and then subsequently transmitting the JPEG image.
In a preferred embodiment, the apparatus further comprises input means for inputting image information in a raster format, and counting means for counting the number of lines of the image information input by the input means, wherein the re-transmitting means re-transmits the image information through the second procedure using the number of lines counted by the counting means.
In a preferred embodiment, the apparatus further comprises mode selection means for switching between a direct transmit mode, in which image reading and transmission are performed in parallel, and a memory transmit mode, in which all image information to be transmitted is stored in memory temporarily and then transmitted, wherein the transmitting means transmits an image through the first procedure in a case where the direct transmit mode has been selected by the mode selection means.
In a preferred embodiment, the transmitting means transmits an image through the second procedure in a case where the memory transmit mode has been selected by the mode selection means.
The present invention further provides an image communication apparatus capable of communicating a color image of a predetermined size by color facsimile transmission, comprising: notification means for notifying a receiving destination of number of lines of the color image; and control means for changing method of notification by the notification means.
In a preferred embodiment, the color image is an image that has been compressed in a JPEG format.
In a preferred embodiment, the control means changes the method of notification when redial transmission of an identical object is performed.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.